Alfa Romeo Owners Club of Australia Forum

Technical => 160 Series (90, 75, 164 Sedans) => Topic started by: bteoh on August 13, 2019, 03:14:29 PM

Title: Alfa 75 TS Radiator Fan
Post by: bteoh on August 13, 2019, 03:14:29 PM
I found out recently that my radiator fan wasn't coming on in heavy traffic and the coolant gauge was creeping up past 100 degrees Celsius. I swapped the relays with some  that were on the right inner fender near the right headlamp but still nothing. Was also wondering if the fan should turn on once I switch on the air con? At the moment, the fan doesn't come on when I switch the aircon on (Aircon works). I tried putting 12 volts directly to the fan motor and the fan does work.
Any ideas what could be wrong?
TIA
Title: Re: Alfa 75 TS Radiator Fan
Post by: simmi1983 on August 14, 2019, 10:18:48 AM
Put power and earth directly to the fan motor, from memory they are only a 2 pin plug. If it doesn't work it's kaput. If it works you'll need to check fuses and relay.

Luke
Title: Re: Alfa 75 TS Radiator Fan
Post by: GTVeloce on August 15, 2019, 12:18:44 PM
The fan won't necessarily turn on when you switch the AC on. The way it is wired the signal must pass through the trinity switches (high and low pressure) and so it might not need the fan to operate. I recently spent quite some time trying to work out the wiring for the radiator in my 75 TS but my problem was different. The fan worked fine foe engine temp but never with AC.

The wiring for engine fan operation is very simple and therefore easy to diagnose. AC operation is a bit trickier. The relay for the AC compressor and rad fan are next to each other, on the right hand fender. Both should have fuses built in however, the fan needs 30amp fuse while the AC a 10amp fuse.

My suggestion would be check the fuse for both relays (in case they have been swapped around). If they are ok, then bridge the two wires that attach to the rad temp switch (round bronze thing on the bottom ride side of the rad - easiest to access from underneath the car or remove the intake snorkel). With the ignition on that should start the fan. If that works then the problem is most likely in the switch. If it doesn't then you will just have to systematically work your way through all connections and wires till you find the problem. Thankfully there isn't many and they are all fairly easy to access.
Title: Re: Alfa 75 TS Radiator Fan
Post by: bteoh on August 15, 2019, 03:07:12 PM
Hey Julian,
Thanks for that. I was wondering if the fan does come on once the aircon is switched on and you have answered that. With my GTV6, when the aircon is switched on, one of the two fans comes on and I wondered whether it was the same for the 75TS.
I shall try to bridge the radiator fan switch wiring and see if that is the problem.
Thanks once again :)
Title: Re: Alfa 75 TS Radiator Fan
Post by: GTVeloce on August 15, 2019, 04:14:16 PM
Always welcome. If you need it I have the wiring diagram I can send you. Just PM your email address.
Title: Re: Alfa 75 TS Radiator Fan
Post by: bteoh on August 18, 2019, 11:02:27 PM
It was a faulty radiator fan switch. Bridged the terminals and the radiator fan works. Removed the switch and swapped it with a used one that I removed from a spare car. Put it back on without losing too much coolant. But since I used the old aluminium washer, I now have a small leak. Tried to buy a new washer from Repco but they donít have one that size. Not sure where I can locate such a washer   :(
Title: Re: Alfa 75 TS Radiator Fan
Post by: bonno on August 19, 2019, 11:19:35 AM
Available on line at the following links. Just need to know your ID and OD dimensions. Whatever you do, don't substitute a copper washer in its place (dissimilar metals will corrode parent metal on contact) . 
https://www.probolt-australia.com/aluminium/aluminium-nuts-washers/aluminium-washers-flat.html?limit=24
or
6 pack washers of assorted sizes.
https://www.mxstore.com.au/p/DRC-Alloy-M8-5Pc-Gasket-Washers/D59-52-540?gclid=CjwKCAjw7uPqBRBlEiwAYDsr1waOAlEjigFlDqH8zaRSYaNcxetS3br8mWf5RAZn2sfxEYxWMEgy7BoCDzwQAvD_BwE
Title: Re: Alfa 75 TS Radiator Fan
Post by: bteoh on August 20, 2019, 12:01:49 AM
Thanks Bonno .
Unfortunately the size of the washer is about 28mm outer diameter and inner diameter about 22mm. Nothing at all listed on those links that you sent. Managed to find a VW washer that might fit. Will check out if that is readily available.
Cheers
Title: Re: Alfa 75 TS Radiator Fan
Post by: bazzbazz on August 20, 2019, 06:44:21 AM
Have you tried your local fastener specialist (Bolt King ect)
Title: Re: Alfa 75 TS Radiator Fan
Post by: rowan_bris on August 20, 2019, 07:07:43 AM
  If they are about 22mm ID then they have the same ID as early sump plug washers, so any Alfa place should have heaps of them.  Otherwise Bursons perhaps?
Title: Re: Alfa 75 TS Radiator Fan
Post by: Colin Edwards on August 20, 2019, 08:07:23 AM
Aluminium can be annealed.  Similar to procedure for copper.  The use of a "Sharpie" is novel!

https://makeitfrommetal.com/how-to-anneal-aluminum-the-beginners-guide/

Probably need to anneal twice. 

After initial anneal, the washer will need to be flattened and any high spots removed.  Use a steel roll or gal water pipe of some sort on a very flat surface - just like rolling pastry!

The washer will be work hardened a bit after rolling so this is a good time to lap the surfaces.  Valve paste or VERY fine wet n dry lubricated with kero will do the job.  Then anneal again.
Title: Re: Alfa 75 TS Radiator Fan
Post by: bteoh on August 20, 2019, 01:13:17 PM
Thanks all for the replies.
Managed to get one from my local Alfa specialist (He had a box full of aluminium washers). Also picked up a spare new Facet switch as a back up. All good to go and hopefully get it installed when I have some time tomorrow arvo.  :)